import datetime
from typing import Iterable, Optional, Any, List

from app import app
from app.extensions import db
from app.models.bridges import BridgeConf, Bridge
from app.models.base import Group
from app.terraform.terraform import TerraformAutomation


class BridgeAutomation(TerraformAutomation):
    template: str
    """
    Terraform configuration template using Jinja 2.
    """

    template_parameters: List[str]
    """
    List of parameters to be read from the application configuration for use
    in the templating of the Terraform configuration.
    """

    def create_missing(self) -> None:
        bridgeconfs: Iterable[BridgeConf] = BridgeConf.query.filter(
            BridgeConf.provider == self.provider,
            BridgeConf.destroyed.is_(None)
        ).all()
        for bridgeconf in bridgeconfs:
            active_bridges = Bridge.query.filter(
                Bridge.conf_id == bridgeconf.id,
                Bridge.deprecated.is_(None)
            ).all()
            if len(active_bridges) < bridgeconf.number:
                for i in range(bridgeconf.number - len(active_bridges)):
                    bridge = Bridge()
                    bridge.conf_id = bridgeconf.id
                    bridge.added = datetime.datetime.utcnow()
                    bridge.updated = datetime.datetime.utcnow()
                    db.session.add(bridge)
            elif len(active_bridges) > bridgeconf.number:
                active_bridge_count = len(active_bridges)
                for bridge in active_bridges:
                    bridge.deprecate(reason="redundant")
                    active_bridge_count -= 1
                    if active_bridge_count == bridgeconf.number:
                        break
        db.session.commit()

    def destroy_expired(self) -> None:
        cutoff = datetime.datetime.utcnow() - datetime.timedelta(days=0)
        bridges = [b for b in Bridge.query.filter(
            Bridge.destroyed.is_(None),
            Bridge.deprecated < cutoff
        ).all() if b.conf.provider == self.provider]
        for bridge in bridges:
            bridge.destroy()
        db.session.commit()

    def tf_prehook(self) -> Optional[Any]:
        self.create_missing()
        self.destroy_expired()
        return None

    def tf_generate(self) -> None:
        self.tf_write(
            self.template,
            groups=Group.query.all(),
            bridgeconfs=BridgeConf.query.filter(
                BridgeConf.destroyed.is_(None),
                BridgeConf.provider == self.provider
            ).all(),
            global_namespace=app.config['GLOBAL_NAMESPACE'],
            **{
                k: app.config[k.upper()]
                for k in self.template_parameters
            }
        )

    def tf_posthook(self, *, prehook_result: Any = None) -> None:
        outputs = self.tf_output()
        for output in outputs:
            if output.startswith('bridge_hashed_fingerprint_'):
                parts = outputs[output]['value'].split(" ")
                if len(parts) < 2:
                    continue
                bridge = Bridge.query.filter(Bridge.id == output[len('bridge_hashed_fingerprint_'):]).first()
                bridge.nickname = parts[0]
                bridge.hashed_fingerprint = parts[1]
                bridge.terraform_updated = datetime.datetime.utcnow()
            if output.startswith('bridge_bridgeline_'):
                parts = outputs[output]['value'].split(" ")
                if len(parts) < 4:
                    continue
                bridge = Bridge.query.filter(Bridge.id == output[len('bridge_bridgeline_'):]).first()
                del(parts[3])
                bridge.bridgeline = " ".join(parts)
                bridge.terraform_updated = datetime.datetime.utcnow()
        db.session.commit()